International study on prevalence of itch: examining the role of itch as a major global public health problem

Abstract

Background

Very few studies have evaluated the global prevalence of pruritus.

Objectives

To assess its prevalence according to age, sex, ethnicity and geographic region.

Methods

An international cross-sectional study was conducted in 20 countries from January to April 2023. Participants were asked to complete a questionnaire on sociodemographics, and to confirm the presence or absence of a skin disease in the last 12 months and the presence or absence of pruritus in the last 7 days.

Results

The studied sample included 50 552 individuals. The worldwide prevalence of pruritus was 39.8%. The age group ≥ 65 years had the highest prevalence (43.3%). The prevalence was 40.7% among women and 38.9% among men (P < 0.001). There was no significant difference between ethnicities (P = 0.14). Compared with North America (41.2%), the prevalence of pruritus was significantly lower in Europe (35.9%, P < 0.001), Australia (38.4%, P = 0.017), East Asia (40.2%, P = 0.04) and Latin America (36.5%, P < 0.001), and higher in Africa (45.7%, P = 0.007). No significant difference was found with the Middle East (40.2%, P = 0.36). The prevalence of pruritus in BRICS countries (40.3%) was significantly higher than that in developed countries (38.7%) (P < 10^–3).

Conclusions

Out analysis is limited because there is no information about the severity or type (acute, chronic) of pruritus. The global prevalence of pruritus revealed age, sex and geographic region differences, with no ethnic differences.

Lay Summary

Itch (or pruritus) is a common symptom that most people will experience at some point in their life. However, very few studies have evaluated the global prevalence of pruritus (or proportion of people with itch).

This study aimed to assess the prevalence of pruritus. To do this, different participants were asked to complete a questionnaire concerning their age, sex, geographic region and ethnicity. We found that compared with North America, the prevalence of pruritus was lower in Europe, Australia, East Asia and Latin America, and higher in Africa. We found no difference in the Middle East.

In conclusion, our findings confirmed a worldwide high prevalence of pruritus with age, sex and geographic region differences, but there were no ethnicity differences.

Author Video: https://youtu.be/1YDuN5OUt_E

What is already known about this topic?

• The impact of demographic factors on pruritus has rarely been assessed, with most studies limited to one region.

What does this study add?

• We conducted an international study to assess the prevalence of pruritus according to age, sex, ethnicity and geographic region on the prevalence of pruritus.

Pruritus (itch) is a common symptom that is experienced by everyone at some point in their lives. It is particularly prevalent in patients with inflammatory skin diseases and in those with systemic and neuropathic conditions.¹ However, very few studies have evaluated the prevalence of pruritus in the general population, with or without skin disease. Studies conducted have been mostly limited to one region.^2,3 The objective of this international study was to assess the worldwide prevalence of pruritus according to age group, sex, ethnicity and geographic region.

Patients and methods

Study design

This study was conducted within the framework of Project ALL. Project ALL is a cross-sectional observational study, launched at the end of 2022, aiming to collect data on all skin types (ALL Skins), all skin diseases (ALL Dermatoses) and all phototypes (ALL Colors) in order to build a large international database (see https://www.alltheskins.com/).

Data collection and sample size

The survey was conducted by a polling company (HC Conseil, Paris, France) between January and April 2023. The study population was selected from Megabase (Kantar Health, New York, NY, USA), a mega database used for market research and opinion surveys, including more than 200 million email addresses worldwide. A representative sample of the general population aged 16 years or more was recruited in 20 countries using stratified, proportional sampling with a replacement design.

In each of the 20 countries in which it was conducted (Table S1; see Supporting Information), proportional quota sampling was used based on the distribution of the population according to age, sex, environment (large cities, towns and rural areas) and income, in order to guarantee national representativeness of the sample. The sample size per country also depended on the ability of the referenced panels in each country to extract a representative sample.

Baseline data on the sociodemographic distribution of the population in each country were extracted from the Eurostat database, updated at the time of the survey, and supplemented by United Nations data.⁴

The eligibility of a respondent was based on demographic data, which were used to create a quota-based sample. When a quota was filled, subsequent people in this category were no longer eligible. Selected participants from all the respective countries were contacted by personal email inviting them to take part in a survey without any specification of the subject of the survey. This prevented a self-selection bias because participants with a skin disease might have been more prone to participate in the study if its purpose had been disclosed. If contact was not successful, another potential participant with the same sociodemographic characteristics was selected randomly. To ensure the robustness of the data collected, individuals who did not complete the whole survey were excluded.

Questionnaire and outcomes

Participants were asked to complete a structured digital questionnaire with various sociodemographic data, and to confirm the presence or absence of a skin disease in the last 12 months and the presence or absence of pruritus in the last 7 days (Figure S1; see Supporting Information). In countries where legislation permits, a question on ethnic origin was also asked.

The questionnaire for data collection was designed in English by the scientific committee of Project ALL, which includes expert dermatologists and public health specialists.

Once created, the questionnaire was administered to a small sample to ensure that the questions were properly understood. It was then translated into each language by native speakers living in the country concerned. To ensure linguistic similarity and cultural coherence between different language versions, the translations produced by native speakers were then translated back into English.

Statistical analysis

Qualitative and ordinal variables were described by their number and frequency. Quantitative variables were described by their mean value, standard deviation, median and distribution. In each country, the total population of individuals was calculated by direct extrapolation of the proportions from the proportionally stratified sample in each country.

We calculated the prevalence of pruritus according to age group (16–39 years, 40–64 years, ≥ 65 years), sex (male, female), ethnicity (Asian, Black, Mixed, White, Other), geographic regions (North America, Europe, Africa, East Asia, South America) and development status: developed countries (USA, Canada, European countries, Australia, Israel) vs. BRICS countries (as of April 2023 in our study: Brazil, India, China and South Africa).

The comparison test used, between the modalities of the qualitative variables, was determined by means of the Z-test. The quantitative variables were compared using Student’s t-test. The risk of a type 1 error (α) was set at 0.05 for all tests. Multiple pairwise comparisons using Tukey’s honestly significant difference test was conducted to compare the groups pairwise, and the Shapiro–Wilk test was performed to assess the normality of the residuals from the statistical model. Finally, we performed univariate and multivariate analyses using logistic regression to assess the odds ratios of all the studied variables (age, sex, geographic region and ethnicity).

The statistical analyses were carried out using HARMONIE 1.7 software, registered with the French Patent and Trademark Office (INPI) (since 25 April 2013) under the name DSE-HARMONIE, registration no. 4000937.

Ethical committee

Data collection was done following the ethical codes of the European Society for Opinion and Marketing Research (ESOMAR) in compliance with General Data Protection Regulation (GDPR) rules [Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data, and repealing directive 95/46/ec (GDPR)].^5,6

Results

The survey covered 20 countries representing more than 50% of the world’s population. Taking into account only individuals aged 16 years or older, the sample was drawn from a total population of 3 213 401 122 people.

The studied sample included 50 552 individuals, 25 388 (50.22%) men and 25 164 (49.78%) women. A total of 40.7% reported having or having had a skin disease in the past 12 months (10.9% atopic dermatitis or eczema, 4.7% psoriasis, 6.3% chronic hand eczema, 3.63% rosacea and 19.0% acne). When asked if they had suffered from itch in the last 7 days, 39.8% answered yes (taking into account the weighting of each country).

Among those stating they had a skin disease, the prevalence of pruritus was approximately 55.7% vs. 28.8% among those who did not (Table 1). The skin diseases with the most complaints of pruritus were atopic dermatitis (72.6%), chronic hand eczema (79.6%) and psoriasis (63.0%).

Table 1

Prevalence of pruritus in different populations according to sex and the presence/absence of skin diseases

Country	Proposed sample sizes per country (N = 50 552)	Overall prevalence of pruritus n (%)	Men (N = 25 388) n (%)	Women (N = 25 164) n (%)	With skin disease n (%)	Without skin disease n (%)
USA	5000	2057 (41.1)	993 (40.0)	1064 (42.2)	850 (59.1)	1207 (33.9)
China	5000	1902 (38.0)	1026 (39.8)	876 (36.2)	1182 (59.8)	720 (23.8)
Germany	4000	1322 (33.1)	643 (32.0)	679 (34.1)	630 (53.3)	692 (24.6)
France	4000	1251 (31.3)	494 (25.3)	757 (37.0)	500 (50.9)	751 (24.9)
India	3000	1278 (42.6)	631 (40.1)	647 (45.4)	822 (57.4)	456 (29.1)
Italy	4001	1504 (37.6)	697 (35.1)	807 (40.1)	636 (54.8)	868 (30.6)
Canada	2500	1044 (41.8)	498 (38.8)	546 (44.8)	467 (58.7)	577 (33.9)
South Korea	2500	1002 (40.1)	514 (40.1)	488 (40.1)	658 (57.0)	344 (25.6)
Brazil	4001	1548 (38.7)	748 (38.2)	800 (39.2)	849 (48.6)	699 (31.0)
Australia	2000	768 (38.4)	372 (37.4)	396 (39.4)	354 (58.2)	414 (29.7)
Spain	4000	1543 (38.6)	709 (36.1)	834 (41.0)	741 (58.4)	802 (29.4)
Mexico	2500	823 (32.9)	340 (28.0)	483 (37.6)	458 (46.0)	365 (24.3)
Poland	2500	1088 (43.5)	478 (38.9)	610 (48.0)	517 (62.6)	571 (34.1)
Portugal	1000	354 (35.4)	162 (33.8)	192 (36.9)	178 (50.7)	176 (27.1)
UAEa	750	334 (44.5)	220 (42.6)	114 (48.9)	187 (57.5)	147 (34.6)
Denmark	1000	325 (32.5)	157 (31.3)	168 (33.7)	171 (49.0)	154 (23.7)
South Africa	1000	511 (51.1)	228 (47.20)	283 (54.74)	276 (69.2)	235 (39.1)
Senegal	300	47 (15.7)	18 (12.0)	29 (19.3)	25 (35.7)	22 (9.6)
Israel	1000	369 (36.9)	160 (32.13)	209 (41.63)	180 (52.9)	189 (28.6)
Kenya	500	239 (47.8)	103 (41.70)	136 (53.75)	130 (58.3)	109 (39.4)

^aUAE was not a BRICS member at the time of this study.

Regarding age, our study showed a significant difference in the prevalence of pruritus between age groups (P < 0.0001). The elderly population (≥ 65 years of age) had the highest itch prevalence. There was a significant difference between age groups 16–39 years and 40–64 years (P < 0.0001), between age groups 16–39 years and ≥ 65 years (P < 0.0001) and between age groups 40–64 years and ≥ 65 years (P < 0.0001) (Figure S2; see Supporting Information). There was a significant difference in the pruritus prevalence between women (40.7%) and men (38.9%) (P < 0.001) (Figure S2).

The prevalence of pruritus according to ethnicity is represented in Figure 1. Statistical analysis did not find a significant effect of ethnicity on the prevalence of pruritus (P = 0.14). Additionally, the pairwise comparisons between ethnic groups revealed that none of the comparisons reach statistical significance.

Figure 1

Prevalence of pruritus according to different ethnicities: Asian, Black, Mixed, White and Other.

Overall, there was a significant difference in the prevalence of pruritus in the six different geographic regions (P < 0.0001). It was significantly higher in Africa (45.7%, P = 0.007), followed by North America (41.2%). Compared with North America, the prevalence of pruritus was significantly lower in Europe (35.9%, P < 0.001), Australia (38.4%, P = 0.017), East Asia (40.2%, P = 0.04) and Latin America (36.5%, P < 0.001). No significant difference was found in the Middle East (40.2%, P = 0.36) (Figure S3; see Supporting Information). Moreover, BRICS countries had a significantly higher prevalence compared with developed countries (40.3% vs. 38.7%, P < 10^–3).

Characteristics of the respondents categorized by self-reported skin disease/no self-reported skin disease are represented in Table 2. Results of univariate and multivariate analyses are represented in Table 3.

Table 2

Patient characteristics, according to presence or absence of skin disease

Pruritus prevalence	With skin disease, n (%)	Without skin disease, n (%)
Women	5636 (55.7)	4482 (17.8)
Age, years
16–39	4630 (50.3)	3809 (16.3)
40–64	4141 (60.6)	4416 (20.3)
≥ 65	1040 (65.7)	1273 (23.4)
Geographic region
Europe	3373 (55.1)	4014 (27.9)
North America	1317 (58.9)	1784 (33.9)
Africa	431 (62.3)	366 (33.0)
Middle East	367 (55.2)	336 (31.0)
Latin America	1307 (47.6)	1064 (28.3)
Asia	2662 (58.3)	1520 (25.6)
Australia	354 (58.2)	414 (29.7)
Ethnicity
Black	653 (55.1)	612 (32.0)
Asian	2793 (58.5)	1661 (26.0)
White	4613 (57.1)	5303 (30.4)
Mixed	923 (48.9)	780 (31.7)

Table 3

Univariate and multivariate analyses

Variable	Univariate analysis		Multivariate analysis
	OR (95% CI)	P-value	OR (95% CI)	P-value
Women	1.185 (1.143–1.228)	< 10–3	1.055 (1.016–1.096)	0.004
Age > 40 years	1.172 (1.131–1.216)	< 10–3	1.325 (1.275–1.378)	< 10–3
Skin disease	3.096 (2.980–3.216)	< 10–3	3.185 (3.062–3.312)	< 10–3
Geographic region
Europe	0.857 (0.826–0.889)	< 10–3	0.918 (0.850–0.992)	0.03
North America	1.168 (1.111–1.227)	< 10–3	1.112 (1.022–1.210)	0.01
Asia	1.091 (1.044–1.140)	< 10–3	0.957 (0.859–1.067)	0.4
Latin America	0.919 (0.871–0.970)	0.002	0.784 (0.717–0.857)	< 10–3
Africa	1.298 (1.181–1.427)	< 10–3	1.221 (1.065–1.399)	0.004
Ethnicity
Asian	1.094 (1.048–1.142)	< 10–3	1.310 (1.173–1.463)	< 10–3
Black	1.124 (1.044–1.211)	0.002	1.386 (1.236–1.554)	< 10–3
White	1.048 (0.989–1.111)	0.1	1.451 (1.324–1.590)	< 10–3

CI, confidence interval; OR, odds ratio.

Discussion

Skin conditions are a public health concern, affecting between 30% and 70% of people worldwide, and are the most frequent reason for consultation in general practice.^7–10

This study is the first to survey a large sample of 20 countries (including China and India) representing more than half the world’s population in the same time frame, with the same questionnaire, while taking into account the demographic weight of each country.

In our study, the global prevalence of pruritus was 39.8%. A study in Oslo showed a prevalence of acute itching reaching 8.4% in the general population by using a categorization ‘no, a little, very much, quite a lot’, and 27% by using dichotomous variables.¹¹

In a cross-sectional study (n = 11 730), chronic pruritus was reported in around 16% of German workers.² In 2003, a survey including a representative sample of the French population showed that the estimated prevalence of chronic pruritus during the 24 months prior to the survey was 12.4%, and the estimated current prevalence was 5.4%.⁷ Another national French study in 2012 showed that 32% of people complained of pruritus during the past week.³ The difference in these results can mostly be attributed to surveys assessing different types of itch (acute such as the Oslo study and chronic in the German and French studies), as well as the different populations and times of studies. It seems from these studies that North Europeans may report less itch than other populations.

As we would expect, pruritus prevalence is higher in those who reported skin diseases (56%), in particular those with atopic dermatitis, chronic hand eczema and psoriasis.

Our study confirmed that pruritus is more common in older patients, ≥ 65 years of age. Xerosis is probably the most common cause of pruritus in this population, in addition to neuropathic changes, immunosenescence and other age-related dermatoses.^12,13 In the German study,² the prevalence increased with age from 12.3% (16–30 years old) to 20.3% (61–70 years old). The French study³ showed no direct association between prevalence of pruritus and age.

Our study corroborates the findings of the study conducted in the Johns Hopkins Health System (n = 18 753),¹⁴ which showed that women are more likely to present with pruritus. There was indeed a significant difference between sexes when considering pruritus prevalence and severity. A German study on chronic pruritus reported sex differences in characteristics and morbidities of pruritus. In fact, women reported more stinging, warmth and pain sensations, and men were likely to have pruritus resulting from systemic or dermatological diseases.¹⁵

It has long been said that pruritus varies significantly across different ethnic populations. This is mostly because several pruritic dermatoses occur more frequently in certain ethnicities.¹⁶ Surprisingly, in our study there was no overall difference in the prevalence of pruritus according to ethnicity. However, a difference was noted in the prevalence of pruritus across geographic regions. Compared with North America, the prevalence of pruritus was significantly higher in East Asia and Africa, and lower in Europe, Australia and South America. The difference might be attributed to differences in access to care and health equalities across these countries. The prevalence of pruritus was, as expected, significantly lower in developed vs. BRICS countries, as lower socio-economic status and health behaviours have increased morbidities.^17–19 For instance, in the Norwegian study,¹¹ 84% of the sample population was Norwegian, 5% were immigrants from Western countries and 3% were immigrants from the Indian subcontinent. Pruritus was found to be significantly more prevalent in men from East Asia and Middle East/North Africa, compared with Norwegians (7%). However, psychosocial factors were possible confounders, as non-Norwegians were immigrants. Finally, multivariate analysis shows that the presence of skin disease is the most influential important variable associated with pruritus, indicating that individuals with skin disease are approximately three times more likely to experience pruritus compared with those without skin disease, while controlling for other factors. Variables such as age and different geographic backgrounds also showed a significant association. Multivariate analysis did not show a higher risk of pruritus among Black ethnicity.

We acknowledge some limitations. The data in most of the participating countries show very high levels of internet use, but there are some countries, such as Senegal and South Africa, in which lower rates of internet use are indicated, which might lead to selection bias in these countries. Moreover, we did not distinguish between the prevalence of chronic (duration ≥ 6 weeks) and acute (duration < 6 weeks) pruritus, as the study assessed the presence of pruritus in the past 7 days. There is also no information about the severity of pruritus, and we could not confirm clinical information about the skin diseases reported.

In conclusion, the prevalence of pruritus according to demographic factors associated with pruritus has so far received minimal attention. A higher prevalence was shown in patients ≥ 65 years old and in women. Moreover, compared with North America, pruritus was more prevalent in East Asia and Africa, was less prevalent in Europe, South America and Australia, and no significant difference was noted in the Middle East region. Further studies are necessary to clarify biologic factors that may lead to differences in the prevalence of pruritus in different populations.

Funding sources

This study was funded by the Patient Centricity, Pierre Fabre.

Data availability

The data that support the findings of this work are available from the corresponding author on reasonable request.

Ethics statement

Data collection was done in respect of ethical codes of the European Society for Opinion and Marketing Research (ESOMAR) in compliance with General Data Protection Regulation (GDPR) rules; ID RCB: 2022-A01859-34.

Patient consent

All individuals gave their consent with the understanding that their information may be publicly available.

Supporting Information

Additional Supporting Information may be found in the online version of this article at the publisher’s website.

Appendix 1: Author affiliations

¹Dr. Phillip Frost Department of Dermatology and Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, Miami, FL, USA

²Faculty of Medicine, Sorbonne University, Paris, France

³Hôpitaux de Paris (AP-HP), Paris Saclay University, Ambroise Paré Hospital, Boulogne Billancourt, France

⁴Corporate Medical Direction Pharma, Dermocosmetics Care & Personal Care, Pierre Fabre, Toulouse, France

⁵Patients Priority Department, EMMA, Paris, France

⁶European Market Maintenance Assessment (EMMA), Paris, France

⁷European Market Maintenance Assessment (EMMA), Tel Aviv, Israel

⁸Dermocosmetics Care & Personal Care, Pierre Fabre, Toulouse, France

⁹Patient Centricity Department, Pharma, Dermocosmetics Care & Personal Care, Pierre Fabre, Toulouse, France

¹⁰Dermatologist, Paris, France

¹¹Société Française des Sciences Humaines de la Peau, Président, Maison de la Dermatologie, Paris, France

¹²CEReSS-EA 3279, Centre d’études et de recherches sur les services de santé et la qualité de vie, Aix Marseille Université, service de dermatologie, CHU de la Timone, APHM, Marseille, France

¹³University of Brest, LIEN, Brest, France

¹⁴Department of Dermatology, Venereology and Allergology and French Expert Centre on Pruritus, University Hospital of Brest, Brest, France

Author notes

The full list of author affiliations is provided in Appendix 1, at the end of the paper.

G.Y. and C.S. contributed equally to the manuscript as first authors; B.H., M.A.R. and L.M. contributed equally as last authors.

Conflicts of interest M.S.A., N.P.C. and C.B. are employed by the Pierre Fabre Laboratory. G.Y., C.S., C.T., M.I., Y.B.H., B.H., M.A.R. and L.M. have no conflicts of interest in this study.